Had my Arachnids installed today on P85D. SC set tire pressures at 47 all around. Fairly harsh ride home. Lowered to 44 at home, and came here. Door sticker says 45 psi, but that’s for 19” Michelin Primacy.
Here's what I got from an older service manual. Tire pressures are pretty much adjust to taste; for 21" tires anywhere from 35 to 45 is safe, all long as you don't exceed the maximum stated on the sidewall of the tire, from there do you like a softer or firmer ride? The former might give a lower lap time, but the latter will yield higher range. Carrying 4 passengers and luggage on a road trip? increase them. Not many people do this.
Never go by the pressure on the tire. That is the recommended max. Always go by the pressure listed on the sticker on the door jamb of the driver's door.
...so I will be deinstalling the OEM 19" wheels on my wife's 2015 S70D and installing the referral award 21" arachnids. Door sticker only reflects 19" tires so pressures (45 PSI) will not be correct. is there a 'replacement' door sticker with the correct pressures for the staggered 21s (I assume 42 PSI)?
no you won't get a replacement door sticker though you could ask... just set your tires to 42 psi with the 21" and you will be fine
Thanks--wow, 40 PSI. Seems low for a Model S. The spec for my P3D+ and 20" square setup Michelins is 42.